Pharmacological Modulation of Perceptual Learning and Associated Cortical Reorganization

TLDR

The pharmacological basis of perceptual learning and cortical reorganization is not well understood. Perceptual learning was induced by Hebbian coactivation of the right index finger tip skin in humans. Placebo improved two‑point discrimination on the coactivated finger, an effect blocked by an NMDA receptor antagonist and doubled by amphetamine, with no drug effects on the contralateral finger, and the magnitude of cortical reorganization correlated linearly with these pharmacological modulations.

Abstract

The pharmacological basis of perceptual learning and associated cortical reorganizations remains elusive. We induced perceptual learning by Hebbian coactivation of the skin of the tip of the right index finger in humans. Under placebo, tactile two-point discrimination was improved on the coactivated but not on the left index finger. This augmentation was blocked by an N-methyl-D-aspartate-receptor blocker, but doubled by amphetamine. No drug effects were found on the left index finger. The individual amount of cortical reorganization as assessed by mapping of somatosensory evoked potentials was linearly correlated with the pharmacological modulation of discrimination thresholds, implying that perceptual learning and associated cortical changes are controlled by basic mechanisms known to mediate and modulate synaptic plasticity.